ST. LOUIS - When Interstate 64 near St. Louis closes for the biggest highway project in the state's history, representatives of hospitals, fire departments and ambulance agencies hope they are ready. The Missouri Department of Transportation's $535 million plan calls for rebuilding more than ten miles of highway, several bridges and 12 interchanges from St. Louis to suburban Frontenac. That stretch includes at least nine medical centers commonly reached by the interstate, which is also known as U.S. 40. Ambulance firms will meet soon with transportation officials to discuss how the construction plan affects their ability to transport patients. Hospital officials met with highway engineers last week.